Apparatus for trimming odontological casts



v. s. WICKHAM. APPARATUS FOR TRIMMING ODONTOLOGICAL' CASTS.

I APPLICATION FILED MAR. 2 1. 1919- 1",331,302. Patented Feb. 17, 1920.

VINCENT SCHOFIELD WICKHAM, 0F WORCESTER, MASSACHUSETTS.

APPARATUS FOR, TRIMMING ODONTOLOGICAL CASTS.

Specification of Letters Patent.

Patented Feb. 17, 1920.

Application filed March 21, 1919. Serial No. 284,007.

To all whom it may concern:

Be it known that I, VINCENT Scr-rormnn .VICKHAM, acitizen of the United States, residing at Vorcester, in the county of Worcester and Commonwealth of Massachusetts, have invented a new and useful Improvement in Apparatus for Trimming Odon'tological Casts, of which the following, together with the accompanying drawings, is a specification.

My present invention relates to an apparatus for trimming the plaster casts employed by dentists representing the upper and lower sets of teeth as represented in perspective view in Fig. l, the cast containing the teeth of the upper jaw being termed the capital. and that containing the teeth of the lower jaw being termed the base. These casts, when taken from the mold or impression tray, are more or less rough and irregular and require to be carefully trimmed both on the upper and lower surfaces and around their edges. This trimming, so far I am aware, is universally performed by hand, the operator holding the cast and trimming it with knife, with the result that the trinnning is more or less irregular and the desired outline is difiicult of attainment.

It is the purpose of my present. invention to provide'an apparatus provided with adjustable means for holding the casts in proper position to be trimmed and for guiding the knife in the operation of trimming, whereby those portions of the cast to be removed may be definitely and accurately determined. These objects, among others, I accomplish by means of an apparatus illustrated in the accompanying drawings, in which Figure 1 is a perspective view of the completed casts containing the teeth of the upper and lower jaws.

2 is an outline of a cast when released from the mold or impression tray.

Figs. 3 and represent in outline the upper and lower casts respectively after the same have been trimmed.

Fig. 5 is a plan View of the holding frame with the parts in position for trimming side No. 1, Fig. 4.

Fig. 6 is a View similar to Fig. 5 with the parts in position for trimming side No. '2, Fig. 4.

Fig. 7 is a side elevation of the holding lower surfaces to form the base.

frame with a portion shown in section on the plane of the broken line 7-7, Fig. 5, and

Fig. 8 is a detail view showing the shoulder which forms the guide for the reciprocating chisel. I

Similar reference characters refer to similar parts in the different figures.

Referring to Fig. 1 of thedrawings, a rep resents the upper cast or capital and b the lower east or base in their completed form, and c, Fig. 2, represents in outline the form of both capital and base taken from the mold. The casts have the outline shown at c, Fig. 2, are trimmed upon their upper surfaces to form the capital and upon their Each cast is then trimmed upon its edges in the shapes represented in Figs. 3 and a, that represented in Fig. 8 being trimmed upon the edges 1, 2, 3, 4t, 5, G and 7, and that represented in Fig. 4% being trimmed upon the edges 1, 2, 3, 6 and 7.

In Figs. 5 and 6 I have represented in plan view holding frame for the plaster casts, provided on one edge with a shoulder serving as a guide for a manually operated knife and containing an adjustable cutter for smoothing the upper and lower edges of the casts. The holding apparatus consists of a plate preferably having a wooden base (Z, Fig. 7,, covered on its upper surface with a plate of sheet metal 0. The plate (Z is rabbeted at one edge to form a shoulder and base as represented in Fig. 8, over which the metal plate 6 is extended. An opening 71, Figs. and 7 is formed through the plate to receive a cutting knife 2' placed at an oblique angle to the surface of the plate, said opening it being enlarged at the bottom as shown at j for the free release of the portions of the cast as the latter is reciprocated back and forth over the edge of the cutting knife 2' in trimming the broadside surfaces of the casts,which is the first operation in trinnning. The position of the cast during this operation is shown at c, Fig. 7. Upon the top of the holding plate I pivot a bar 7: by means of a bolt 7e held in the plate and carrying a wing nut 75 by which the bar 7; may be tightened in any desired position. The opposite end of the bar 70 carries a bolt k having an enlarged head which is movable in an undercut groove 76 concentric with the bolt 76, said groove 711* communicating with a similar undercut groove 70 parbar and passing through the slot m ofthe bar m. The bolt m carries a wing nut m enabling the .two bars 70 and m to be locked together. The bolt 70 is provided with a wing nut 70 and held in the slot m is a bolt m having an enlarged head movable in the undercut slot 70? and provided with a wing nut m In Fig. 5 I have shown a cast 0 represented by broken lines in a position for trimming the broadside of the cast by its movement over the knife 11, and I have also shown the outline of a cast 0 in position for trimming the edge 1, with the bars hand m placed in position for supporting the cast 0 against movement as the edge 1 is being trimmed. The bars ]t' and m are moved into proper position to contact with the curved surface of the cast 0, with one edge of the cast 'overhanging the rabbeted edge at of the holding plate. A chisel pointed knife 0 is then reciprocated across the overhanging edge of the cast until the plastic material has been cut away on a line corresponding with the rabbet n.

A readjustment of the bars 70 and m is then made, as indicated in Fig. 6, to afford suitable support to the cast 0 in position for trimming the edge 2. For this purpose, the cast is made to overhang the rabbet a, represented in Fig. 6, and the overhanging edge is then cutaway by the reciprocation of the chisel pointed knife 0, the amount of the plastic cast to be removed being determined bythe overhang of the cast over the rabbeted edge a of the plate. Other adjustments of the slotted bars k and m are then made for the purpose of accurately trimming the remaining edges 3, 4, 5, 6 and 7 of the casts. By the above method of trimming, great accuracy is secured in the trimmed casts, the only care-required is in placing the casts with the proper overhang of the casts over the rabbeted edge a.

I claim,

1. In an apparatus of the character described, a supporting plate for the cast, bars adjustable on said plate to contact with the edges of the cast, and means for attaching said bars to the plate in their adjusted positions.

2. In an apparatus of the character described, a supporting plate for the cast, bars adjustable on said plate to contact with the edges of the cast, means for attaching said bars to the plate in their adjusted positions, and a guideway for a reciprocating knife.

3. In an apparatus of the character described, a supporting plate for the cast, bars adjustable on said plate to contact with the edges of the cast, means for attaching said bars to the plate 1n thelr adjusted posltlons,

said plate being rabbeted at one of its edges to form a guideway for a reciprocating knife, and a knife inserted in said plate for trimming the broadside surfaces of the cast.

I. In an apparatus of the character described, a supporting plate provided with means for trimming the broadside surface of a cast and having one of its edges rahbeted to provide a shoulder for a reciproeating knife, and means adjustable on said plate to contact with the edges of a cast.

In an apparatus of the character de scribed, a supporting plate for the cast,

"means adjustable on said plate tocontact with the edges of the cast, means for retaining said contacting means in their adjusted position, and a guide for a reciprocating knife parallel with one of the edges of the plate.

6. In an apparatus of the character de scribed, a supporting plate for the cast, a slotted bar pivotally attached at one end to said plate and having its opposite end adjustably held in a slot concentric with the pivot of the bar, a second slotted bar ad justably held in the slot of said pivoted bar and having one of its ends adjustably held on said plate.

7. In an apparatus of the character de scribed, a supporting plate for the cast, a slotted bar pivotally held on said plate, said plate having a curved groove. concentric with the pivot of said bar and a straight line groove communicating with said curved groove,-a;second slotted bar crossing said pivoted bar, means for adjustably connecting said bars, and means for attaching said second bar to said plate.

VINCENT SCHOFIELD WICKHAM. Witnesses RUrUs B. FO LER,

PENELOPE CoMBnnBAon. 

